The term “object” used in this specification should be expansively construed to cover any kind or specimen of wafers, masks, reticles and other structures, combinations and/or parts thereof used for manufacturing semiconductor integrated circuits, magnetic heads, flat panel displays, and other semiconductor-fabricated articles. Various objects such as semiconductor wafers, printed circuit boards, solar panels and micro-electromechanical devices are fabricated by manufacturing processes that are highly complex and costly, comprise multiple stages, and require highly accurate machines.
The term “defect” used in this specification should be expansively construed to cover any kind of abnormality or undesirable feature formed on or within a wafer.
The complex manufacturing process of objects is not error-free and such errors may cause faults in the manufactured objects. The faults may include defects that can harm operation of the object, and nuisances, which may be defects, but do not cause any harm or malfunction of the manufactured unit. Errors may be caused during the manufacturing process, due to faults in the raw material, mechanical, electrical or optical errors, human errors or others, which may cause defects in the wafers. Further defects may be caused by spatio-temporal factors, such as temperature changes of the wafer occurring after one or more captures during the examination process, which may cause slight deformations of the wafer.
Unless specifically stated otherwise, the term “examination” used in this specification should be expansively construed to cover any kind of detection and/or classification of defects in an object. Examination is provided by using non-destructive inspection tools during or after manufacture of the object to be examined. By way of non-limiting example, the examination process can include runtime scanning (in a single or in multiple scans), sampling, reviewing, measuring, classifying and/or other operations provided with regard to the object or parts thereof using the same or different inspection tools Likewise, examination can be provided prior to manufacture of the object to be examined and can include, for example, generating an examination recipe(s). It is noted that, unless specifically stated otherwise, the term “examination” or its derivatives used in this specification are not limited with respect to resolution or size of inspection area. A variety of non-destructive inspection tools includes, by way of non-limiting example, scanning electron microscopes, atomic force microscopes, optical inspection tools, etc.
The examination process can also introduce further alleged errors, for example due to optical, mechanical or electrical problems in the examination equipment or process which thus provide imperfect captures. Such errors may produce false positive findings, which may seem to contain a defect, but there is no actual defect at the area.
Unless specifically stated otherwise, the term “image” used in the specification should be expansively construed to cover any non-destructive capturing of an object, including, but not limited to, capturing by an optical device, capturing by a scanning electron microscope, or by any other device. The term may also relate to a processed captured image, to a combination of two or more captured images, to a synthetically generated visual representation of an object or part thereof manufactured upon description, such as design data of the object, or the like.
Some techniques for examining objects for defects include comparing a captured image of an object to a reference image, wherein differences between the images may suggest a possible defect in the examined object at the location of a difference. However, such comparison may not always be straightforward due, inter alia, to differences between the images which are not related to possible defects. For example certain elements cannot be identified at either image at all or at an expected location, due for example to location mismatch, size mismatch, color or shade mismatch, or the like. The problems may be caused by defects which may be present in the object and need to be detected, problems occurring during capturing the object, such as but not limited to optical or mechanical problems, thus disabling or damaging registration, and other causes.